Tape tension adjusting device including a movable chassis carrying a rotatable arm which is adapted to engage a stop pin on a stationary chassis

ABSTRACT

A tape tension adjusting device includes a tension arm rotatable in accordance with a tape tension, a restricting member for restricting the rotation of the tension arm when the tape tension applied is more than a predetermined value and a pressing mechanism for pressing the tension arm against the restricting member when the tape is not running.

This application is a continuation of application Ser. No. 07/802,212,filed Dec. 4, 1991, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a tape tension adjusting device, and moreparticularly, to a device for adjusting the tension of a magnetic tapein a magnetic recording/reproducing apparatus, such as a video cassetterecorder (VCR), a digital audio tape recorder (DAT) or the like.

2. Description of the Related Art

In a recording/reproducing apparatus using magnetic tape as a recordingmedium, such as a VCR, a DAT or the like, a magnetic tape receivedwithin a tape cassette is drawn from the tape cassette, and arecording/reproducing operation is performed while pressing the magnetictape against a recording/reproducing magnetic head, such as a rotatinghead or the like.

FIG. 1 shows a tape loading mechanism of a so-called helical-scanningVCR wherein a tape is drawn from a cassette and is helically woundaround a rotating head drum to perform a recording/reproducingoperation.

In FIG. 1, there are shown a cassette C, a supply-side reel SR and atakeup-side reel TR.

There is also shown a main chassis 101. A rotating head drum 102 isrotatably mounted on the main chassis 101 in an inclined state at apredetermined angle, and is rotated at a high speed by a motor (notshown).

Movable tape guide posts 103-106 draw a tape 116 from the cassette Cmounted on the main chassis 101, and wind it around the rotating headdrum 102 to form a tape path shown in FIG. 1. The movable tape guideposts 103-106 are operated by a well-known mechanism (not shown). Afixed guide post 107 for forming the tape path is provided on the mainchassis 101. A capstan 108 drives the tape 116. A pinch roller 109presses the tape 116 against the capstan 108 to run the tape 116.

A supply-side reel mount 128 and a takeup-side reel mount 132 engage thesupply-side reel SR and the takeup-side reel TR within the mountedcassette C to rotate the reels, respectively. These reel mounts 128 and132 are rotatably driven by well-known means (not shown).

A tension regulator arm (hereinafter termed a tension arm) 110 maintainsthe tension of the tape 116 running along the tape path at a constantvalue to provide good contact of the tape 116 with head drum 102. Thetension arm 110 is rotatably disposed on the main chassis 101 via a pin110a provided at one end of the tension arm 110. A pin 112 contactingthe tape 116 is provided at the other end of the tension arm 110. Thetension arm 110 is biased in a direction to press the pin 112 againstthe tape 116 by the elasticity of spring 114, and is connected to oneend of a belt 130 wound around the outer circumference of thesupply-side reel mount 128.

When the tension arm 110 is biased in a counterclockwise directiondirection by spring 114, the supply-side reel mount 128 is braked bysurface contact with the belt 130. When the tension arm 110 rotates in aclockwise direction, the belt 130 is loosened to reduce braking actionapplied to the supply-side reel mount 128.

When the tape 116 runs in the state shown in FIG. 1, if back tensionapplied to the tape 116 is reduced due to a change in the amount of thetape 116 wound around the supply-side reel SR, the tension arm 110 isrotated in a counterclockwise direction by the spring 114 to tighten thebelt 130 around reel mount 128. The back tension, i.e., the load in thetape running system, changes as the diameter of the tape 116 woundaround the reel SR changes, thus changing the rotational moment inrotating reel SR. Hence, the supply-side reel mount 128 is braked toincrease the back tension, and the original tension is restored.

When the back tension on the tape 116 increases, the tension arm 110 isrotated in a clockwise direction against the spring 114 to loosen thebelt 130. Hence, the brake force applied against the supply-side reelmount 128 is lessened to reduce the back tension, and the originaltension is recovered.

In order to perform a stable recording/reproducing operation, it isnecessary to apply a predetermined tension to the tape 116. As describedabove, since the tension arm 110 detects a change in the tape tensionand automatically corrects the tension, it is possible to alwaysmaintain the tape tension at a predetermined value.

According to the tape loading mechanism, in an unloading state whereinthe tape 116 is received within the cassette C, the movable guide posts103-106, the pinch roller 109 and the pin 112 of the tension arm 110 aresituated inside the tape 116 within the cassette C, as indicated bybroken lines in FIG. 1. When the tape loading mechanism operates, themovable guide posts 103-106, the pinch roller 109 and the pin 112 of thetension arm 110 draw the tape 116 from within the cassette C to providea loading state wherein the tape path shown in FIG. 1 is formed.

The above-described tape loading mechanism, however, has the followingproblems.

That is, in a normal tape running state wherein the tape 116 runs in thedirection of arrow A (the forward direction) shown in FIG. 1, the tapetension must be maintained constant. When the tape 116 is running, thetension arm 110 is free, and a change in the tape tension is detected tocontrol the braking effect of the belt 130, as described above. Thebrake for the supply-side reel mount 128 is thereby controlled tomaintain the tape tension constant.

When the tape 116 stops, the tape 116 must be loosened because the tape116 may be damaged if an unnecessary tension is applied to the tape 116.

When the tape 116 runs in a direction reverse to the direction of arrowA (in a reversal playback operation or the like), since the capstan 108is at a side downstream from the rotating head drum 102 in the forwardrunning direction of the tape 116, the entire running system from therotating head drum 102 to the takeup-side reel mount 132 becomes therotation load, and the tape 116 is wound by the reel mount 128 which haspreviously been at the supply side. Accordingly, at the position of thetension arm 110, the tape 116 is pulled by the supply-side reel mount128 to provide an excessive tension on the tape 116. As a result, thetension arm 110 is displaced by rotating in a clockwise directionagainst the spring 114, causing a change in the running position of thetape 116, whereby the tape 116 may be damaged by contacting the tapeoutlet in the cassette C.

Accordingly, the tension arm 110 must free the tape 116 when the tape118 is running in the forward direction, restrict the tape 116 at aposition where the tape 116 is loosened when the tape 116 stops, andrestrict the movement of the tape 116 due to an excessive tension whenthe tape 116 is running in the reverse direction so that the runningposition of the tape 116 is not changed by the rotation of the tensionarm 110 due to an increase in the tension.

In the above-described tape loading mechanism, however, the tension arm110 is situated inside the tape 116 within the cassette C indicated bythe broken lines in FIG. 1 in an unloading state, draws the tape 116 byrotating in the direction of arrow B in accordance with a tape loadingoperation, and is at the tape loading position shown in FIG. 1.Accordingly, it is impossible to provide means, such as a stopper or thelike, for restricting the position of the tension arm 110 when the tape116 stops or runs in the reverse direction, because such means obstructsthe rotation of the tension arm 110.

Under such a background, in order to perform the position restriction inthe above-described respective operational modes of the tension arm 110,there have been proposed configurations wherein the above-describedstopper is separated from the rotational range of the tension arm 110until the tape loading state is provided, and the tension arm 110 ismoved to a position where it can be restricted after the tape loadingoperation has been completed.

FIGS. 2 and 3 show an example of such configurations. In FIGS. 2 and 3,the same components as those shown in FIG. 1 are indicated by the samereference numerals.

In FIGS. 2 and 3, a stopper arm 134 is rotatably disposed on the mainchassis 101 by a pin 138. A restricting member 134a for restricting theposition of the tension arm 110 is formed at one end of the stopper arm134. A cam follower pin 134b engaging a cam groove 138a formed on a gearboard 138 (to be described later) is provided at the other end of thestopper arm 134.

The cam board 138 functions as a mode control means for setting variouskinds of operational modes including the tape loading mechanism shown inFIG. 1 via a well-known drive transmission mechanism (not shown), and isrotatably disposed on the main chassis 101 via a pin 140. A gear portionformed on the outer circumference of the cam board 138 meshes with gear144 mounted on the rotation shaft of a motor 142, whereby the cam board138 is rotated by the rotation of the motor 142 at a reduced speed.

The cam groove 138a, whose distance from the pin 140 serving as thecenter of rotation changes in accordance with the rotational position,is formed on the cam board 138 so as to control the rotation of thestopper arm 134 by the rotation of the cam board 138 via the cam groove138a.

The relationship between the cam groove 138a of the cam board 138 andthe stopper arm 134 will now be explained. FIG. 2 shows a state in thecourse of tape loading shifting from an unloading state to a tapeloading state. In this state, the cam follower pin 134b of the stopperarm 134 moves along a small-diameter portion of the cam groove 138aduring the unloading state and the tape loading operation, whereby thestopper arm 134 is rotated in a counterclockwise direction and therestricting member 134a is maintained at a position out of therotational range of the tension arm 110. Accordingly, the rotation ofthe tension arm 110 during the tape loading operation is not obstructed.

After the tape loading operation has been completed and the tension arm110 has rotated to its operational position, the cam follower pin 134bof the stopper arm 134 moves from the small-diameter portion to alarge-diameter portion of the cam groove 138a, as shown in FIG. 3, torotate the stopper arm 134 in a clockwise direction. Hence, therestricting member 134a is moved to a position where the rotation of thetension arm 134 can be restricted. It is thereby possible to restrictthe rotational position of the tension arm 110 if an excessive tensionis applied during, for example, a playback operation of the tape in thereverse direction.

In the above-described method of restricting the tension arm using themovable members, however, positional accuracy is reduced due to aclearance between the respective members and the like, whereby, forexample, the stability of the tape tension is reduced, and the tape isdamaged by contacting the cassette because the running position of thetape is deviated, causing a problem from the viewpoint of reliability.

Furthermore, when the tape stops, the tension arm 110 is driven in acounterclockwise direction by the spring 114 to press its pin 112against the tape. Hence, the tension continues to be applied to thetape, causing damage to the tape as described above.

In order to solve the above-described problems, a new stopper forrestricting the tension arm 110 against the spring 114 is needed. Such astopper must be separated from the tension arm 110 in its normalposition because the stopper may obstruct the rotation of the tensionarm 110 during the normal tape running state, and must be in closecontact with the tension arm 110 only when the tape stops. In addition,the stopper cannot be provided within the rotational range of thetension arm 110.

However, it is almost impossible to provide a movable stopper mechanismfor dealing with excessive tape tension to be used when the tape is notrunning at both sides of the tension arm 110, in consideration oflimited space, complication of the configuration, and relationship withother mechanisms. Accordingly, in the above-described tape loadingmechanism, it is impossible to provide complete means for restrictingthe tension arm 110.

SUMMARY OF THE INVENTION

It is an object of the present invention to solve the above-describedproblems of the prior art.

It is another object of the present invention to provide a tape tensionadjusting device which provide a high-precision fixed positioning meanswithout obstructing the operation of a tension arm, and which can alwayshighly precisely restrict a tape tension and a tape position.

It is still another object of the present invention to provide a tapetension adjusting device which restricts the position of a tension armin a plurality of operational modes by pressing the tension arm againsta common fixed member to improve positional accuracy, and which canrestrict the tension arm by the common fixed member both when anexcessive tension is applied and when the tension arm is forcedly fixedwhen the tape is not running.

These objects are accomplished, according to one aspect of the presentinvention, by a tape tension adjusting device, comprising an adjustingmember in contact with a running tape, with the adjusting memberincluding a pivoting pin for rotating in accordance with a tensionapplied by the tape. In addition, a restricting member restricts therotation of the adjusting member when the tension applied by the tape ismore than a predetermined value, and pressing means presses theadjusting member against the restricting member when the tape is notrunning.

According to another aspect of the present invention, the tape tensionadjusting device comprises a rotatably mounted adjusting member incontact with the running tape, with the adjusting member rotating aboutone end in accordance with a tension applied by the tape. In addition, astationary restricting member restricts rotation of the adjusting memberwhen the tension applied by the tape is more than a predetermined value.

According to the above-described configuration, the tension arm, oradjusting member, is restricted by the restricting member even if atension applied is more than the predetermined value, for example, whilethe tape is running in the reverse direction, whereby the tension arm isprevented from being rotated more than necessary. When the tape is notrunning, the tape can be in a non-tensioned state by pressing thetension arm against the restricting member by the pressing means. Sinceit is only necessary to increase the positional accuracy of therestricting member, the production and assembly of the device can beeasily performed, whereby the production cost can be reduced.

The foregoing and other objects and features of the present inventionwill become apparent from the following detailed description of thepreferred embodiment taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a tape loading mechanism of a helicalscanning VCR;

FIG. 2 is a diagram showing a tension arm restricting method using amovable member in the prior art, and represents a case wherein a tape isrunning in the forward direction;

FIG. 3 represents a case wherein a tape is running in the reversedirection in the method shown in FIG. 2;

FIG. 4 is a diagram showing an embodiment of the present invention, andrepresents a tape unloading state;

FIG. 5 represents a tape loading state in the embodiment shown in FIG.4;

FIG. 6 is a plan view of a tape tension adjusting device when a tape isrunning according to the embodiment; and

FIG. 7 is a plan view of the device when the tape stops.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A tape tension adjusting device according to the preferred embodiment ofthe present invention will now be explained in detail. First, an outlineof the embodiment will be briefly described.

Recently, for the purpose of providing a small loading mechanism for aVCR, there have been developed tape loading mechanisms configured suchthat, after loading a cassette at a loading position on a main chassis,the cassette itself is further slid to the side of a rotating head drumin accordance with a tape loading operation to provide a tape loadingstate wherein part of the rotating head drum is received in a recessformed at a front surface of the tape-drawing side of the cassette.

In a device of this kind, a slide chassis which slides on the mainchassis while mounting the cassette is disposed so as to be able toslide back and forth relative to the rotating head drum. A supply reelmount, a takeup reel mount, a tension arm and the like are also disposedon the slide chassis.

Even in such a mechanism, the same approach as in the above-describedprior art is adopted for the restriction of the tension arm in variouskinds of operational modes, and so far no countermeasures have beenprovided. Accordingly, the above-described problems remain as problemswhich are inevitable for the tension arm.

The present embodiment relates to this mechanism. In the presentembodiment, a fixed restricting member is provided at a position whichis out of the rotational range of a tension arm in a tape unloadingstate wherein a slide chassis mounting a cassette is separated from arotating head drum, and which is within the rotational range of thetension arm after the rotation of the tension arm to its operationalposition has been completed in a tape loading state wherein the slidechassis advances to the rotating head drum. The positional restrictionof the tension arm in a plurality of operational modes is performed bypressing the tension arm against the fixed restricting member, therebyincreasing positional accuracy. The tension arm can be restricted by thecommon fixed restricting member both when an excessive tension isapplied and when the tension arm is forcively fixed in the case that thetape is not running.

That is, by utilizing the movement wherein the slide chassis providedwith the tension arm slides in accordance with the tape loadingoperation, a configuration for restricting the position of the tensionarm by forcedly pressing the tension arm against the fixed member isprovided.

A detailed explanation will now be provided of a tape loading mechanismof a VCR in the tension adjusting device of the present embodiment withreference to the drawings.

FIGS. 4 and 5 show a tape loading mechanism in a VCR. FIG. 4 representsa tape unloading state, and FIG. 5 represents a tape loading state.

In FIGS. 4 and 5, there is shown a main chassis 1. A rotating head drum2 is rotatably mounted on the main chassis 1 in an inclined state at apredetermined angle via a drum base 3, and is configured so as to herotated at a predetermined high speed by a drum motor (not shown).

A tape-entrance-side movable guide post 4a draws a tape from within acassette C and winds the tape around the rotating head drum 2 at apredetermined angle from a tape-entrance side in a tape loadingoperation, and is moved along a guide groove 3a formed in the drum base3 by a driving system (to be described later).

A tape-exit-side movable guide post 4b draws the tape from within thecassette C and winds the tape T around the rotating head drum 2 at thepredetermined angle from a tape-exit side in a tape loading operation,and is moved along a guide groove 3b formed in the drum base 3 by adriving system (to be described later).

A capstan 8 is rotated by a motor (not shown) to move the tape. Amovable inclined guide post 4c is operatively linked with thetape-exit-side movable guide post 4b by a driving system (to bedescribed later) to draws the tape and guide the tape to the capstan 5(in the position shown in FIG. 5). The operational position of theinclined guide post 4c is positioned by a positioning member 1c.

A fixed guide post 18, and a guide roller 6 which comprises an impedanceroller are disposed in the main chassis 1. A positioning member 20 forpositioning a tension arm (to be described later) is formed at a portionfor mounting the fixed guide post 18 on the main chassis 1.

A movable chassis (hereinafter termed a slide chassis) 7 is disposed soas to be slidable back and forth relative to the rotating head drum 2 onthe main chassis 1 by means of long holes 7a and 7b in the slide chassis7 and pins 1a and 1b on the main chassis 1. A cassette mounting unit 71is formed on the upper surface of the slide chassis 7. In the unloadingstate shown in FIG. 4, the slide chassis 7 retracts from the rotatinghead drum 2 so that the cassette C can be detached. In a state whereinany of various kinds of operational modes can be adopted after thecompletion of tape loading as shown in FIG. 5, the slide chassis 7advances to the rotating head drum 2 so that part of the rotating headdrum 2 is received within a recess C1 in the front surface of thecassette C, whereby the space is reduced, and it becomes possible toprovide a small device.

A supply reel mount 28 and a takeup reel mount 32 are rotatably disposedon the slide chassis 7, engage a supply reel SR and a takeup reel TR oftile mounted cassette C, respectively, and drive these reels indirections corresponding to the operational mode with a speedcorresponding to the mode. These reel mounts are rotatably driven by areel motor (not shown).

A tension arm 10 is rotatably disposed on the slide chassis 7 via a pin10a, is driven in a counterclockwise direction by a spring 14, detectsthe tape tension by pressing the tape 16 drawn from the supply reel SRagainst a tension post 12, and maintains the tape tension constant by acontrolling brake applied from a belt 30 wound around the circumferenceof the supply reel mount 28. The configuration and operation of thisportion will be described in detail later.

A pinch roller lever 8 supports a pinch roller 8a pressed against thecapstan 5 while receiving the tape 16 between the pinch roller 8a andthe capstan 5 (see FIG. 5). A movable guide post 9 guides the tape 16passing the capstan 5 to the takeup reel TR within the cassette C.

A cam board (named a mode cam) 22 for mode control is rotatably disposedon the main chassis 1 via a pin 22a. The cam board 22 is rotated by amotor (not shown) to run the tape loading operation and the tapeunloading operation by operating the slide chassis 7, the respectivemovable guide posts 4a-4c and 9, the pinch roller lever 8 and thetension arm 10 via drive transmission mechanisms (not shown). The camboard 22 also sets various kinds of operational modes (for example,recording, playback, quick-feeding, rewinding, high-speed search, stillplayback, slow playback, reverse playback, stop and the like) in thetape loading state. A cam groove 22b comprising a large-diameter portionand a small-diameter portion with respect to the center of rotation forcontrolling the rotation of a tension arm restricting lever 24 (to bedescribed later) is formed on the upper surface of the cam board 22.

One end of the tension arm restricting lever 24 is rotatably mounted onthe main chassis 1 via a pin 24a. A leaf spring 26 for restricting theposition of the tension arm 10 by pressing the tension arm 10 againstthe mounting base 20 of the fixed guide post 18 in accordance with anoperational mode is mounted on the other end of the tension armrestricting lever 24. A cam follower pin 24b engaging the cam groove 22bin the upper surface of the cam board 22 for mode switching is formed onthe lower surface of the tension arm restricting lever 24.

According to the above-described configuration, the tension armrestricting lever 24 is rotated by the cam groove 22b in accordance withthe rotation of the cam board 22, and the position of the tension arm 10is restricted in accordance with the operational mode of the tension armrestricting lever 24. The operation of the tension arm restricting lever24 will be described in detail later.

The tape loading mechanism in the present embodiment has theabove-described configuration. In the tape unloading state shown in FIG.4, the slide chassis 7 is separated from the rotating head drum 2 sothat the cassette C can be mounted on a cassette mounting unit 71 of theslide chassis 7.

When the cassette C is mounted on the slide chassis 7 in this state, themounted state of the cassette C is detected by well-known means, and theadvancing operation of the slide chassis 7 is started. In this state,all of the movable guide posts 4a, 4b, 4c and 9, and the pinch roller 8aare situated inside the tape 16 within the cassette C, the tension arm10 is rotated in a clockwise direction against the spring 14, and theguide pin 12 for detecting tape tension provided at the distal end ofthe tension arm 10 is also received inside the tape 16 within thecassette C.

In the above-described state, the mounting base 20 of the fixed guidepost 18 for restricting the position of the tension arm 10 is separatedfrom the rotational range of the tension arm 10, and is in a positionalrelationship with the tension arm 10 so as not to obstruct the rotationof the tension arm 10 in a tape loading operation.

If the mounted state of the cassette C is detected in this state asdescribed above, a loading motor (not shown) rotates to start therotation of the cam board 22 for mode switching. The slide chassis 7mounting the cassette C thereby starts to advance via a drivetransmission mechanism (not shown), the movable guide posts 4a-4c and 9,the pinch roller 8a, and the pin 12 of the tension arm 10 start to moveoutside the cassette C, and a tape loading operation for drawing thetape from within the cassette C and loading the tape to the rotatinghead drum 2 and the capstan 5 is started. Thus, the tape path shown inFIG. 5 is formed to provide a tape loading state.

The cassette C on the slide chassis 7 is advanced to the rotating headdrum 2, a state wherein part of the drum 2 is received within the recessC1 in the front surface of the cassette C is provided, and the tapeloading state is thereby provided.

The important point is that the present embodiment is configured so thatby the advancing sliding operation of the slide chassis 7, the mountingbase 20 which is out of the rotational range of the tension arm 10 inthe tape unloading state shown in FIG. 4 assumes a position within therotational range of the tension arm 10 where the position of the tensionarm 10 can be restricted, and the tension arm 10 is rotated to theposition in the tape loading state shown in FIG. 5 by passing thetension arm 10 in front of the mounting base 20 before the mounting base20 enters within the rotational range of the tension arm 10.

That is, in the tape loading state, as is apparent from FIG. 5, themounting base 20 must be situated within the rotational range of thetension arm 10 because the mounting base 20 restricts movement of thetension arm 10. However, if the mounting base 20 is provided at such aposition in a tape unloading state, the mounting base 20 obstructs therotation of the tension arm 10, whereby it becomes impossible to performa tape loading operation.

In the present embodiment, in a tape loading operation, the mountingbase 20 formed on the main chassis 1 is situated outside the rotationalrange of the tension arm 10 until the tension arm 10 is rotated to theoperational position in the tape loading state utilizing the slidingmovement of the slide chassis, and the mounting base 20 is situatedwithin the rotational range after the completion of the movement of thetension arm 10 to the operational position. Thus, the above-describedproblems are solved. In a tape unloading operation, since the tensionarm 10 rotates into the cassette C and returns after the slide chassis 7has retracted From the mounting base 20, the mounting base 20 of coursedoes not obstruct the operation of the tension arm 10.

An explanation will now be provided of the operations of the tension arm10, and the mounting base 20 and the lever 24 For restricting theposition of the tension arm 10 with reference to FIGS. 6 and 7.

In FIG. 6, as described above, the guide pin 12 is set on the distal endportion of the tension arm 10 rotatable around the pin 10a. The tensionarm 10 is always biased in a counterclockwise direction by the spring14. The tension arm 10 is at the position indicated by solid lines whenthe tape is running in the Forward direction, and is at the positionindicated by one-dot chain lines when the tape is running in the reversedirection. The magnetic tape 16 is drawn from the tape cassette. Theguide post 18 guides the magnetic tape 16, and is fixed on the chassis 1via the mounting base 20. The mounting base 20 is precisely positionedso as to restrict the rotation of the tension arm 10 in a clockwisedirection due to the contact of the tension arm 10 with a side surfaceof the mounting base 20 when the tape is running in the reversedirection, as will be described in detail later.

The cam groove 22b is formed in the cam board 22 rotatable around theshaft 22a. The lever 24 is rotatable around the pin 24a. The pin 24b seton a side surface of the lever 24 enters the cam groove 22b of the camboard 22, whereby the lever 24 rotates around the pin 24a in accordancewith the rotation of the cam board 22. The leaf spring 26 is mounted onthe distal end portion of the lever 24. The lever 24 and the leaf spring26 are provided in a position so as to release the tension arm 10 whenthe tape 16 is running, as shown in FIG. 6, and to force the tension arm10 to contact the mounting base 20 when the tape is not running, asshown in FIG. 7.

The tension belt 30, one end of which is fixed on the main chassis 1, isfixed on the tension arm 12 while being wound around the reel mount 28.

In the above-described configuration, when the tape 16 runs in theforward direction (represented by arrow 32), the tape tension is weakbecause the resistance applied to the tape in contact with guide posts4a-4c and 9, pinch roller 8a and capstan 5 occurs downstream from thetension arm 10 in the direction of the running tape. Thus, the tensionarm 10 rotates in a counterclockwise direction and is positioned by thetension belt 30. In this case, the leaf spring does not bias the tensionarm 10, which occupies the position indicated by the solid lines in FIG.6. Then the tape 16 runs in the reverse direction, the tape tension ishigh because the resistance applied to the tape in contact with guideposts 4a-4c and 9, pinch roller 8a and capstan 5 occurs upstream Fromthe tension arm 10 in the direction of the running tape. Thus, thetension arm 10 is rotated and driven in a clockwise direction, and stopsat the position (the position indicated by the one-dot chain lines) ofcontacting the mounting base 20.

As shown in FIG. 7, when the tape is not running, the lever 24 rotatesin a counterclockwise direction due to the rotation of the cam board 22,and the leaf spring 26 presses the tension arm 10 against the mountingbase 20. The tape 16 is thereby loosened, assuming a non-tensionalstate.

In the present embodiment, when the tape is running in the reversedirection, the tension arm 10 is restricted by the mounting base 20which is precisely positioned. Hence, accuracy in the restrictingposition of the guide pin 12 determining the path of the tape can beeasily obtained. When the tape is not running, it is only necessary topress the tension arm 10 against the mounting base 20 by the leaf spring26. Hence, high accuracy is not required for the components, and it isonly necessary to use simple components.

Although, in the present embodiment, the mounting base 20 for the guidepost 18 is used for restricting the rotation of the tension arm 10, anyother member fixed to the main chassis 1, the guide post 18 itself orthe main chassis 1 itself may of course be used in place of the mountingbase 20. Furthermore, any other elastic member may be used in place ofthe leaf spring 28. In addition, the lever 24 may be driven by asolenoid.

As can be easily understood from the foregoing explanation, according tothe present embodiment, it is possible to realize accuracy in the tapeposition using members having low precision, and therefore to largelyreduce the production cost.

According to the tension adjusting device of the present embodiment, theposition restriction of the tension arm in the plurality of operationalmodes is performed by pressing the tension arm against the common fixedmember to improve positional accuracy, and the tension arm can berestricted by the common fixed member both when an excessive tension isapplied and when the tension arm is forcively fixed when the tape is notrunning. Furthermore, it is possible to provide a high-precision fixedpositioning means without obstructing the operation of the tension arm,and to precisely restrict tape tension and a tape position.

What is claimed is:
 1. A recording and/or reproducing apparatus forperforming recording and/or reproducing of signals on a tape-likerecording medium, said apparatus comprising:a head drum including atleast one head; a first chassis for mounting said head drum; a secondchassis movably disposed relative to said first chassis and capable ofmounting the medium thereon; a plurality of guiding members for guidingthe recording medium to said head drum; an adjusting member, rotatablymounted on the second chassis, in contact with the tape, said adjustingmember including a pivot point and rotating about the pivot point inaccordance with a tension applied by the recording medium; and arestricting member, mounted on said first chassis to be stationary atall times, for restricting rotation of said adjusting member when thetension applied by the recording member is more than a predeterminedvalue.
 2. An apparatus according to claim 1, further comprising pressingmeans for pressing said adjusting member against said restricting memberwhen the recording medium is stationary.
 3. An apparatus according toclaim 2, wherein said pressing means presses said adjusting memberagainst said restricting member to restrict its rotational movement. 4.An apparatus according to claim 3, wherein said adjusting member extendsin a linear direction and is provided with a guide member at a first endportion thereof and said pivoting pin is disposed at a second endthereof, wherein the tape is in rubbing contact with said guide member.5. An apparatus according to claim 4, wherein said first end portion ofsaid adjusting member contacts said restricting member.
 6. An apparatusaccording to claim 5, wherein said restricting member serves as a basefor supporting one of said guiding members.
 7. An apparatus according toclaim 6, wherein said base is Fixed to said First chassis.
 8. Anapparatus according to claim 2, wherein said pressing means comprises acam and a lever engaging said cam.
 9. An apparatus according to claim 8,wherein said lever has a first end pivotally connected to said firstchassis and a second end provided with an elastic member for pressingagainst said adjusting member.
 10. An apparatus according to claim 9,wherein said cam defines a groove on a rotating member, and wherein aprojection provided on said lever is engaged in said groove.
 11. Anapparatus according to claim 1, wherein said restricting member servesas a base for supporting one of said guiding members.